DESCRIPTION

The Indexer class is Apache Lucy’s primary tool for managing the content of inverted indexes, which may later be searched using IndexSearcher.

In general, only one Indexer at a time may write to an index safely. If a write lock cannot be secured, new() will throw an exception.

If an index is located on a shared volume, each writer application must identify itself by supplying an IndexManager with a unique host id to Indexer’s constructor or index corruption will occur. See FileLocking for a detailed discussion.

Note: at present, delete_by_term() and delete_by_query() only affect documents which had been previously committed to the index – and not any documents added this indexing session but not yet committed. This may change in a future update.

delete_by_term

Mark documents which contain the supplied term as deleted, so that they will be excluded from search results and eventually removed altogether. The change is not apparent to search apps until after commit() succeeds.

field - The name of an indexed field. (If it is not spec’d as indexed, an error will occur.)

term - The term which identifies docs to be marked as deleted. If field is associated with an Analyzer, term will be processed automatically (so don’t pre-process it yourself).

delete_by_doc_id

optimize

$indexer->optimize();

Optimize the index for search-time performance. This may take a while, as it can involve rewriting large amounts of data.

Every Indexer session which changes index content and ends in a commit() creates a new segment. Once written, segments are never modified. However, they are periodically recycled by feeding their content into the segment currently being written.

The optimize() method causes all existing index content to be fed back into the Indexer. When commit() completes after an optimize(), the index will consist of one segment. So optimize() must be called before commit(). Also, optimizing a fresh index created from scratch has no effect.

Historically, there was a significant search-time performance benefit to collapsing down to a single segment versus even two segments. Now the effect of collapsing is much less significant, and calling optimize() is rarely justified.

commit

$indexer->commit();

Commit any changes made to the index. Until this is called, none of the changes made during an indexing session are permanent.

Calling commit() invalidates the Indexer, so if you want to make more changes you’ll need a new one.